The invention relates to a circuit arrangement for a picture display device for generating an essentially sawtooth-shaped line deflection current with a trace and a retrace through a deflection coil, which circuit arrangement comprises a series circuit of a trace capacitor, the line deflection coil and a bidirectionally conducting, line frequency-controlled switch which is conducting during the trace time and is not conducting during the retrace time, in which retrace time the deflection coil and a retrace capacitor are part of a resonant network.
Such a circuit arrangement for a picture display device is generally known. During the trace time the retrace capacitor is short-circuited by the switch, while the deflection coil is connected to the voltage of the trace capacitor, the trace voltage. The line deflection current initially having a linear variation as a function of time flows through the coil. During the retrace time, the retrace capacitor and the coil form part of a resonant network, in which time the current goes from the maximum value in one direction to the same value in the other direction. The periodical opening and closing of the switch at the line frequency thus results in a sawtooth-shaped current through the deflection coil. To fill up losses in the circuit arrangement, a power supply source is provided for generating a DC voltage of high value, often with stabilization facilities for keeping the said value constant. This source is coupled to the deflection circuit by means of a smoothing capacitor of high capacitance and an storage inductance of high value. During the trace time the current flows through the storage inductance and the energy stored therein causes a compensating current to the resonant network during the retrace time. The average value of the trace voltage is substantially equal to the voltage of the source.